Morris Minor Owners Club

Hi, I have a 1961 Morris 1000,000 and am looking to replace the oil filler cap which is dented. The one fitted has a knurled edge about 6mm high with a 1 piece clip underneath. The top has oil companies names stamped into it. All the ones I can find seem to be a lot deeper with a circular round notched catch underneath. Can anyone tell me if the cap I have is an original and if so, does anyone have one for sale? If not, are the replacements I mentioned a concourse quality swap?. Thanks[frame][/frame]